One of the most frequent questions I get is in regards to the bears. No, I am not really concerned about the bears. The black bears on the eastern seaboard are mostly after food - and hikers and campers are not really food to a black bear. What they want are the cookies and snickers and such that they smell in a backpack or food sack. The regular advice is to hang your food bag (or your entire pack) from a tree limb away from your campsite. There is now one section of the trail in Georgia that the forestry department has declared as an area where overnight campers must use a bear canister. From what I have heard, the bears have learned where food is kept and are smart enough and persistent enough to get it. Since this is only a 5 mile section where the regulation is in play, most hikers are simply hiking through it and camping well on the other side. I plan on doing that myself. For everywhere else, I am taking 50 feet of paracord to use to hang my food bag up in the air away from any scavenging bears.
Mice are another source of food theft. Apparently mice frequent shelters on the trail because of the natural hiker food source as well as a place to hide and thrive under the shelter floor. Stories abound about mice chewing through backpacks to get to crumbs. The standard advice is to leave all backpack pockets open and empty so the mice will inspect and not chew. Food bags are also hung inside the shelters from futile attempts to foil the little bastards. A string hung from the ceiling to get your food bag off the ground. To keep the mice from climbing down the string, an empty tuna can is tied in the middle. Unless it's done particularly well, the mice simply jump from the wall or the neighboring string directly onto your food bag and dine to their heart's content. My choice is to avoid the shelters except in the worst weather.